The Yamaha AN1x Synthesizer mailing list

Wall Warts

In a previous job I was a Test Engineer for an independent standards and
compliance lab.  We tested many types of equipment to different regulations
and rules - governmental, military, insurance, whatever.  I personally had
the privilege of working with Korg, Shure, ATT, IBM and other big names.
Here's what I learned about wall warts:

In the USA, the testing requirements for electrical saftey are different for
products which require less than 48 volts input to the chassis.  If a
product required more, it needed to meet tougher standards to be allowed to
be sold, and these standards often would require more circuitry, and
therefore would be more expensive.  Therefore, a lot of companies chose to
have the AC converted down to less than 48 volts through a power converter
(wall wart) and then sent to the device through a small twin lead wire
ending in a small plug.  This design decision was nothing more than a cost
saving feature (detriment) in many cases.

My personal advice on gear that uses wall warts is to make very sure that
you have routed the tiny, skinny cable in a way that nobody trips over it.
I have repaired many circuit boards that were really hurt by a kick or an
unexpected pull on these hard to see wires.  I try to route mine down the
side of the keyboard stand and even sometimes tape it down for safety.

Equipment that has the standard IEC male receptacle on the back - that takes
the fully detachable and rugged cable which gets the full AC voltage from
the wall (and is international in design) is much more rugged in general,
surviving trip overs and other abuse...  It is much more "road worthy".

Generally, all of the curcuitry in a wall wart is usually this: a
transformer, some diodes and maybe some capacitors.  These components can be
easily built into the unit.  Tawdry and cheap design is why we suffer with
these stupid warty chunks of plastic and metal that take up so much space.
In the back of my 12 space rack I have to stuff 5 ugly wall warts which
hardly fit.

Ed Edwards
Leader: Ezekiel's Wheel\ufffd      \ufffd\ufffd\ufffd\ufffdRetro-Progressive Rock\ufffd\ufffd\ufffd\ufffd
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